Photoelectric tube and method of manufacture



Jan. 9, 1951 G. LEWlN ETAL PHOTOELECTRIC TUBE AND METHOD OF MANUFACTURE Filed April 22, 1947 Patented Jan. 9, 1951 FlCE PHOTOELECTRIC TUBE AND METHOD OF MANUFACTURE Gerhard Lewin, Maplewood, and John Benes, Jr.,

Geneva, Ill., assignors to Continental Electric I Company, Geneva, 111., a corporation of Delaware ' Application April 22, 1947, Serial No. 743,040

to cause danger of over-heating of the cathode in forming the press and seal ng-in operations.

One ob ect of this invention is to im rove the construction of the tube, partic larly the mounting of the cathode, whereby it mav be" supported, if desired, in part at least by the wall of the envelope, requiring only a single connection therewith which forms the lead, and is locat d at the center of the lower end of the cathode. The cathode is formed of very thin sheet-metal having sufiicient res liency so that its sides expand lateraly against the walls of the envelope and, therefore, will be supported by the envelope without more than the single connection or lead.

A further objectof the invention is to produce a phototube as small aspossible, and at the same time t'o avoid over-heating of the cathode. A considerable amount of heating is required to form the press, much more than for the sealing of the exhaust tubing onto the glass envelope of the tube. A glass that does not contain lead. such as lime glass, is used to form the envelope, whereas a ead glass of much lower melting point may be used to form the exhaust tubing, to be sealed to the envelo e bv a lower heating ooeration'. The press is formed also of a glass which does not contain a lead oxide. and is formed before the elements are assembled in the envelope.

One embodiment of the invention is illustrated in the accompanying drawings in which:

Fig. 1 is a side elevation of a'phototube and exhaust tube sealed together;

Fig. 2 is a side elevation of the phototube after sealing thereof; and

Fig. 3 is a cross-section therethrough on the line 33 of Fig. 2.

The invention is shown as applied in a phototube of minute size which is, however, exaggerated in the drawings for clearness of i lustration. This phototube may be of a size, for instance, of about one inch in length and threesixteenths inch in diameter, which size, however, ismentioned only as an example;

The phototube illustrated comprises a glass 6 Claims; (Cl. 250-165) 2 envelope I, within which is mounted the usual cathode 2 and anode 3. The getter pill is illustrated at 4 and is shown as mounted on the anode 3, merely for purpose of illustration; it may be mounted in any convenient position within the envelope. 1

The leads for the elements 2 and 3 are shown at 5 and 6, respectively, both sealed within a stem or press 1. Also sealed in the stem or press I are pins l I connected at one end with the leads 5 and 6 and projecting at the opposite end 'fr om the stem or press'to be engaged in a socket or other connector for the celL sup'porting th'e'cell thereby.

Due to the minute size of the envelope l,"the cathode 2 is mounted in an improved manner without requiring the severalsupports ordinarily provided heretofore. In this form of the inven-' tion, the cathode 2 is formed of sheetmetal coated in the usual manner to provide a photoemissive cathode surface, and has sufiicient re'-:

silie'ncy so that it maybe curved between opposite sides of the envelope I, as shown in Fig. 3-,- and wil be supported and retained by the walls of the envelope without requiring the usual 'auxil-- iary supports. Thus only a single connection is needed, the attachment of the lead 5 thereto, and yet the cathode will be retained efiectively in place. This type of mounting is particularly important in a minute tube. While the cathode may expand uniformly throughout a semi-cylindrical portion of the envelope, and. bear thereagainst about its periphery, it is shown as hav ing flaring sides I2 bearing thereagainst only at opposite sides of the envelo e.

To avoid darkening of the envelope in the flashing of the caesium in thepill 4, the envelope is formed ordinarily of a glass which does not contain lead oxide because the lead oxide would be reduced bythe caesium and cause a darkening eiiect on the envelope. We have found that this difliculty can be overcome if the envelope I is made of lime glass, as the material now available for this purpose without the use of lead oxide glass.

The press I is formed with the leads 5 and B inserted therein, before the cathode 2 is mounted thereon. The cathode 2 and the anode 3 and pill 4 are heat-sensitive, and are mounted in the tube I in any suitable manner that will not aiiect the use thereof, after the press I is made. The press is integral with the envelope I, and likewise, must not contain lead oxide.

An exhaust tubulation' is shown at 8, which initially has a. flared end 9, capable of being sealed directly to the end of the envelope i. This tubulation 8 may be formed of lead glass with its relatively low softening point since there would be no tendency for a darkening of the wall of the enevelope from the tubulation itself. Thus less heat is required due to the relatively soft character of the exhaust tubulation, to seal the flared end 9 thereof, to the envelope 1. The glass envelope is not appreciably softened by this sealing action and the heating of the latter is just sufficient to soften the lead glass tubulation.

After the tubulation 8 is sealed to the envelope, the tube is exhausted in the usual manner, and then the end is sealed as indicated at 10, by sealing the inner end of the tubulation 8 in the manner indicated in dotted lines in Fig. 1, and,

in Fig. 2.

In this way, the danger of over-heating of the cathode is avoided, and also the darkening of the=envelope. At the same time, the construction permits the manufacture of the tube in a minute size in a practical manner.

,While the invention is illustrated in one embodiment thereof, as described above, it will be understood that it should not be restricted to this embodiment but that changes may be made in the construction without departing from the invention, except as specified in the claims.

We claim:

1. A phototube comprising an enclosed envelope having a surrounding wall, an anode and cathode mounted in the envelope and each having a lead connected therewith, said cathode including a self-sustaining sheet of material connected with the lead thereof at one end intermediate the width of said sheet, and having flaring sides bearing against substantially opposite sides of the wall of the envelope and supported thereby in bridging relation between said opposite sides.

2. A process of forming a phototube with a glass envelope having a projecting integral stem portion at one end thereof, comprising enclosing leads in said stem portion and applying heat and pressure thereto to seal the leads therein in position with the stem projecting outwardly from the end of the envelope, inserting light sensitive elements within the envelope and connecting them with the leads, sealing an exhaust tubulation to the opposite end of the envelope, exhausting the envelope therethrough, and sealing off the envelope at the inner end of the tubulation.

3. A process of forming a phototube with a glass envelope having a projecting integral stem portion at one end thereof, comprising enclosing leads in said stem portion and applying heat and pressure thereto to seal the leads therein in position with the stem projecting outwardly from the end of the envelope, inserting photo-electric elements within the envelope and connecting them with the leads, sealing an exhaust tubulation to the opposite end of the envelope, exhausting the envelope therethrough, and sealing off the envelope at the inner end of the tubulation.

4. A process of forming a light sensitive tube with an envelope having a press at one end thereof, comprising enclosing leads in said press, inserting light sensitive elements within the envelope and connecting them with the leads, sealing an exhaust tubulation to the opposite end of the envelope, exhausting the envelope therethrough, and sealing off the envelope at the inner end of the tubulation.

5. A process of forming a light sensitive tube with an envelope having a press at one end thereof, comprising enclosing leads in said press inserting photo-electric elements within the envelope and connecting them with the leads, applying an exhaust tubulation having a flaring inner end to the outer end of the envelope with the flaring end closing said end of the envelope, sealing said flaring end to said end of the envelope, exhausting the envelope therethrough, and sealing off the envelope at the inner end of the tubulation outwardly of the flaring end thereof.

6. A process of forming an electric discharge tube with an envelope having a press at one end thereof, comprising enclosing leads in said press, inserting electric discharge elements within the envelope and connecting them with the leads, sealing an exhaust tubulation to the opposite end of the envelope, exhausting the envelope therethrough, and sealing off the envelope at the inner end of the tubulation.

GERHARD LEWIN. JOHN BENES, Ja.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,955,335 Knowles Apr. 1'7, 1934 1,965,585 Foulke July 10, 1934 2,024,585 Laico Dec. 17, 1935 2,161,859 Geffcken et al June 13, 1939 2,330,838 Nelson Oct. 5, 1943 2,420,311 Gowell May 13, 1947 2,424,990 Krim Aug. 5, 1947 2,443,528 Acheson et al June 15, 1948 2,451,043 Pennybacker Oct. 12, 1948 

